The field used in a protocol (such as DNS or ICMP) to indicate how many more network hops are allowed before the packet is dropped (discarded) (and, in terms of a TCP protocol as opposed to a UDP protocol) an error returned to the sender
Transistor Transistor Logic was the initial implementation of the 74xxnnn series logic (TTL being the form with xx omitted)
Through-the-lens metering - Metering that calculates the light coming into the camera from the subject Often used for flashes
An output signal format defined as a rectangular wave capable of driving a multiple of TTL loads It has a positive signal peak greater than +2 4 volts and a negative signal peak less than +0 5 volts The number of loads must be specified (MIL-PRF-55310D, 3 6 20)
TOP Through-the-lens; commonly used when referring to metering through the lens as opposed to via a separate meter Effective for fill-flash and other tricky lighting situations
Abbreviation for transistor-transistor-logic A popular logic circuit family that uses multiple-emitter transistors A low signal state is defined as a signal 0 8V and below A high signal state is defined as a signal +2 0V and above
Metering system in which light-sensitive cells within the camera body measure exposure from image-forming light that has passed through the lens
An integrated circuit family that use bipolar junction transistors to build the logic gates
Transistor-Transistor Logic; a fast, reasonable-cost type of integrated circuit used in some monitors
Transistor-transistor logic TTL logic levels are 0V (low) and +5V (high) The TTL switching threshold is around +1 3V (+2V max) When TTL signals are transmitted using coaxial cables, a 10k-ohm termination to ground is typically used Sometimes 50-ohm drivers are used to transmit fast pulses
a 32 bit signed integer that specifies the time interval that the resource record may be cached before the source of the information should again be consulted Zero values are interpreted to mean that the RR can only be used for the transaction in progress, and should not be cached For example, SOA records are always distributed with a zero TTL to prohibit caching Zero values can also be used for extremely volatile data
A camera design that let's you compose an image while looking at the scene through the lens that will take the picture Also called thru-the-lens
(TITLE) - normally the title of the page addressed by the URL This property is filled in automatically by the server during URL validation, so there is never any need to set it, unless you want to override the site's title